Re: [Xen-devel] [XenARM] XEN tools for ARM with Virtualization Extensions

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Thu, 2013-06-27 at 16:21 +0000, Eric Trudeau wrote:
> > -----Original Message-----
> > From: Ian Campbell [mailto:Ian.Campbell@xxxxxxxxxx]
> > Sent: Wednesday, June 26, 2013 12:45 PM
> > To: Eric Trudeau
> > Cc: xen-devel
> > Subject: Re: [XenARM] XEN tools for ARM with Virtualization Extensions
> > 
> > Is there any chance you could configure your MUA for ">" style quoting?
> 
> Done.

Thank you!

> > > > I also found that xc_dom_elfloader.câs function, xc_dom_guest_type(),
> > > > did not know about the EM_ARM machine type.
> > >
> > > You shouldn't be hitting the elf loader paths, you should instead use
> > > the zImage version of the kernel which will hit the
> > > xc_dom_armzimageloader.c code paths.
> > >
> > > We did at one point in the very early days of the port support loading
> > > ELF files via a quick hack of a tool ("xcbuild") but that has been
> > > superceded by the proper toolstack support and the use of zImage.
> > >
> > > [EPT] I noticed when I used my zImage that it seemed to check for a gzip
> > magic number so I thought maybe I should not use it.
> > > I will go back to using the zImage since I believe the issue is the same. 
> > >  It
> > appears that virt_base and virt_alloc_end are invalid.
> > > I will try to find out how these are supposed to be determined.  Any tips 
> > > would
> > be welcome. :)
> > 
> > This sounds like the XSA-55 regression I referred to. If you pull up to
> > the commit I mention above (which is currently in staging and will
> > propagate to master after automated test, hopefully overnight) then this
> > problem should go away.
> > 
> 
> I rebased to the XSA-55 commit and now I can create the guest.  I am
> able to debug a kernel init panic.

Excellent!

> Thanks so much.
> 
> My next question is why does the wiki for ARM give an example dom.cfg that 
> does not have builder=hvm?
> I tried it and it seems that xc_hvm_build_arm.c does not support building HVM 
> guests yet.

Xen on ARM does not support HVM guests. On ARM guests are a hybrid PV
using hardware extensions where possible, but at the toolstack level we
treat them as PV guests.

You might find one or the other of these slides useful for describing
the sorts of guests which Xen on ARM supports:
http://fr.slideshare.net/xen_com_mgr/xensummit-na-2012-xen-on-arm-cortex-a15
http://www.xenproject.org/help/presentations-and-videos/video/latest/linaro-connect-introduction-to-xen-on-arm.html

HVM, in the sense of emulating a complete real world platform as a
guest, is something which we might eventually do but it is not something
which is currently on our roadmap.

If you are looking to use a non-Linux guest then porting an OS to Xen on
ARM is far more trivial than the PV x86 port. The Linux port to Xen on
ARM was a pretty small amount of code.

Ian.



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